Some products are manufactured on assembly lines that may use conveyor systems to transport articles between two or more processing stations. In some assembly lines, the articles may move in a continuous flow substantially without stopping. In some other assembly lines, the movement of articles may be segmented or indexed by, for example, slowing down or stopping at certain processing stations.
In some assembly lines, motion may be imparted to objects to assemble a product. Motion can be imparted to objects in a variety of manufacturing processes to serve a variety of purposes. Some motion may transport objects from one location to another, such as from one processing station to another. Other motion, such as stirring or stamping, may be imparted to directly process an article.
Various mechanical, pneumatic, and electromechanical devices have been used in manufacturing processes to impart motion that is both desired and useful. Mechanical devices may convert force to a desired motion by employing elements such as cams, gears, pinions, linkages, or pulleys. Pneumatic devices may impart motion using valves, pistons, and hydraulic fluids. Electromechanical devices (i.e., motors) generally impart motion by converting electromagnetic energy to a force.
To impart motion to an object, electric motors can generate torque or thrust. A rotary motor can convert electrical input energy to rotational torque on a shaft. A linear motor can convert electrical input energy to a linear force (i.e., thrust). In general, torque or thrust is a function of motor current.
In some cases, a maximum current rating may be defined for a motor under certain operating conditions. The maximum current rating may determine a maximum motor torque or thrust that may be generated by the motor under those operating conditions. The maximum current rating may be, for example, based in part on thermal characteristics of the motor. For example, a maximum safe temperature in the motor may be used to determine maximum current ratings, such as the maximum average or r.m.s. (root-mean-square) current that may be continuously applied to the motor windings without overheating the motor, and the maximum current ratings may be used to determine a maximum rated torque or thrust.